1. Field of the Invention
The present invention relates to control of thermal fixation of a toner image formed by an electrophotographic method.
2. Description of the Related Art
The provisions of power saving and the like have recently becoming more strict, and image forming apparatuses are required to further reduce power consumption. That is, image forming apparatuses need to further reduce power consumption while maintaining a fixing temperature capable of reliably fixing an image. There is a technique of controlling the fixing temperature of a fixing unit in accordance with the amount of applied toner obtained from image data. Japanese Patent Laid-Open No. 2000-242107 (patent literature 1) discloses a method of determining whether input image data represents a photographic image or a character image, and when fixing a photographic image, making the fixing temperature of the fixing unit higher than that when fixing a character image. According to patent literature 1, the power consumption of the fixing unit can be reduced by adjusting the fixing temperature in accordance with the amount of applied toner representing image data.
An image forming apparatus has a poster printing function and a page division printing function. The poster printing function and the page division function are functions for printing input image data, which is intended to be output to one page, divisionally over a plurality of pages. For example, when printing input image data having an A4 size as an enlarged image having a double size (2×2) in the vertical and horizontal directions, the poster printing function prints it as image data in four (=2×2) pages each having the A4 size. The printed four pages are combined and used as an enlarged output image. On the other hand, for example, when printing input image data having an A4 size of 4-in-1 printing (also called 4-up printing) as an enlarged image having a double size (2×2) in the vertical and horizontal directions, the page division function prints it as image data in four (=2×2) pages each having the A4 size. In this case, four (=2×2) image regions formed as 4 in 1 in an A4 paper sheet are divisionally printed on 4 pages of A4 paper sheets.
However, to use the poster printing function or the page division printing function and control the fixing temperature, it is necessary to control the fixing temperature of each output page in accordance with the layout configuration of the output image to be printed. At the time of poster printing, the plurality of divided printed pages are continuous as image data or independent image data that are not continuous. On the other hand, at the time of page division printing, the plurality of divided printed pages are expected to be printed as independent image data. The above-described conventional technique does not consider the difference between the poster printing function and the page division function, and therefore fixing temperature control according to the image layout configuration is not appropriately performed.